Preparation method of iridium and iridium alloy materials

Abstract

The present invention discloses iridium and iridium alloy materials and methods for preparing them, addressing the challenges of preparing large-scale iridium and iridium alloy materials with high density, fine grains, and preferred grain orientation. This method improves the purity of the green body through hydrogen atmosphere degassing and impurity removal, and uses a ceramic indenter to perform in-situ vacuum, moldless hot rolling and slow deformation, thereby increasing material density, avoiding impurity contamination, and addressing mold usage challenges, enabling the preparation of large-scale, high-performance iridium and iridium alloy materials. The present invention utilizes a rational and easy-to-implement process, resulting in excellent performance for the iridium and iridium alloy materials produced.

Description

Technical Field

[0001] The invention relates to a preparation method of iridium and iridium alloy materials, and belongs to the fields of precious metals, information storage and high-temperature structural materials. Background Art

[0002] Driven by the internet, data volumes across various industries are exploding. To meet the demands for high-density information storage and rapid read / write speeds, the precious metal iridium, a high-value-added specialty electronic material, and its excellent physical and chemical properties have led to its widespread application in information storage applications such as GMR heads, sensors, magnetic random access memories, and signal coupling devices. For example, authorized patents CN102163432 B and CN105304097B describe IrMn composite films as antiferromagnetic layers in GMR heads. Authorized patent CN103426443B describes pure iridium films as the lower layer of heat-assisted magnetic recording (HAMR) media stacks.

[0003] The above-mentioned pure iridium thin films and composite films are usually made of iridium and iridium alloy sputtering targets and are deposited on the surface of a round wafer substrate by magnetron sputtering. In order to form high-quality thin films, the preparation and quality of the target material are extremely critical. At present, the market wafer size has developed to 12 inches, and research and development of larger specifications (14 inches, 15 inches, 16 inches, ...) wafers has begun. Large-size wafers require the target material to also develop in the direction of large size to meet sputtering needs. At the same time, in order to improve the sputtering rate and the uniformity and quality of the sputtering coating, the target material is required to be high-purity, high-density, fine-grained and preferentially oriented.

[0004] Currently, iridium and iridium alloy materials are commonly produced by melt casting and powder metallurgy. The casting method uses medium-frequency induction melting followed by precision casting. However, due to the limited melting point of magnesium oxide crucibles (2800°C), it is difficult to produce large-sized iridium ingots. Impurities such as ceramic crucible components are easily introduced during smelting, resulting in many defects in the cast iridium ingots and difficult to control, and the density of the ingots is not high. The powder metallurgy method places iridium or iridium alloy powder in a graphite mold and sinters it under vacuum hot pressing. The preparation of large-sized iridium and iridium alloy materials is difficult to achieve high density, small and uniform grain size, and preferred grain orientation. At the same time, high temperature and high pressure cause graphite diffusion to contaminate the product, and graphite molds are easily damaged under high temperature and high pressure. Therefore, there is an urgent need to develop new methods for preparing iridium and iridium alloy materials.

[0005] Furthermore, the most widely used high-temperature structural material is nickel-based superalloys. However, the melting point of nickel at 1453°C limits their use in high-temperature environments exceeding 2000°C. Therefore, the development of new, high-performance, ultrahigh-temperature alloys has become a key focus and hotspot in high-temperature structural materials research worldwide in recent decades. Iridium, with its high melting point of 2466°C, is the only metal that can be used in oxidizing atmospheres up to 2000°C without significant degradation, while maintaining excellent mechanical properties above 1800°C in air. Iridium alloys offer stable chemical properties, high hardness, excellent high-temperature performance, excellent corrosion resistance, and high-temperature oxidation resistance. They also possess an fcc / L12 phase structure similar to nickel-based alloys, making them considered an ideal next-generation superalloy, potentially replacing nickel-based alloys as structural materials operating in environments exceeding 2000°C. This demonstrates the broad and irreplaceable potential of iridium and its alloys in the field of high-temperature structural materials.

[0006] In summary, based on the new demands for iridium and iridium alloy materials from technological and industrial development, there is an urgent need to develop methods for preparing iridium and iridium alloy materials with large size, high density, small grains and preferential orientation, so as to further promote the development of technology and industry in the field of information storage and high-temperature structural materials. Summary of the Invention

[0007] To address the shortcomings of the existing technology, the present invention proposes deoxidation and impurity removal in a hydrogen atmosphere to improve the purity of the green body, and enhances the material density through an in-situ vacuum, die-less, hot rolling and slow deformation process. Furthermore, the invention proposes the use of a high-strength ceramic indenter for hot rolling and slow deformation of the green body. This not only avoids impurity contamination but also solves the problem of graphite molds being easily broken under high pressure, enabling the preparation of large-scale, high-performance iridium and iridium alloy materials. This invention represents a significant technological innovation.

[0008] The object of the present invention is to provide a method for preparing iridium and iridium alloy materials, characterized in that:

[0009] (1) pressing iridium powder or iridium-containing mixed powder by steel die pressing or cold isostatic pressing to obtain a green body, wherein the green body has a relative density of 40% to 60%;

[0010] (2) deoxidizing and removing volatile impurities by heating the green body obtained in (1) at 600-1400° C. in hydrogen for 5-300 min;

[0011] (3) The blank obtained in (2) is heat treated in a vacuum at 1000-2300° C. for 5-300 min, and then slowly deformed by in-situ vacuum moldless hot rolling at the same temperature. After the deformation is completed, it is cooled in the furnace to obtain iridium or iridium alloy material.

[0012] Furthermore, in the above technical solution, the purity of the selected iridium powder or iridium-containing mixed powder is not less than 99.9%.

[0013] Furthermore, in the above technical solution, after removing impurities from hydrogen in step (2), a green body with a purity increased by 0.0001-1% is obtained;

[0014] Furthermore, in the above technical solution, other powders in the iridium-containing mixed powder are selected from one or more of manganese, tantalum, platinum, rhenium, tungsten, rhodium, ruthenium, thorium, hafnium, zirconium, niobium, nickel, aluminum, etc.

[0015] Furthermore, in the above technical solution, the weight percentage of other powders in the iridium-containing mixed powder is 0.01%-60%.

[0016] Furthermore, in the above technical solution, the iridium and iridium alloy material has a thickness of 0.01-50 mm and a relative density of >95%.

[0017] Furthermore, in the above technical solution, the grain size of the iridium and iridium alloy material is 0.5-20 μm; preferably 0.5-10 μm; more preferably 0.5-5 μm.

[0018] Furthermore, in the above technical solution, the iridium and iridium alloy material grains are preferentially oriented, and the oriented crystal planes are one or more crystal planes among (111), (200), and (220).

[0019] Furthermore, in the above technical solution, the iridium and iridium alloy material blank is treated in hydrogen at a temperature of 600-1400° C., preferably 800-1300° C., more preferably 1000-1200° C., and the holding time is 5-300 min, preferably 30-120 min.

[0020] Furthermore, in the above technical solution, the vacuum heat treatment temperature of the iridium and iridium alloy material is 1000-2300° C., preferably 1000-1800° C., and more preferably 1100-1600° C. The heat treatment time is 5-300 min, and preferably 30-60 min.

[0021] Furthermore, in the above technical solution, the in-situ vacuum moldless hot rolling slow deformation pressure is 5-50MPa, preferably 30-40MPa. The vacuum degree is 10 -1 -10 -4 Pa; preferably 10 -3 -10 -4 Pa.

[0022] Furthermore, in the above technical solution, the material of the hot rolling slow deformation press head is ceramic, selected from alumina, zirconium oxide, silicon carbide, silicon nitride, and yttrium oxide.

[0023] Furthermore, in the above technical solution, the slow deformation time of hot rolling is 5-300 min; preferably 60-200 min; more preferably 60-120 min.

[0024] The present invention provides the above-mentioned method for obtaining iridium and iridium alloy materials. The iridium and iridium alloy materials have a thickness of 0.01-50 mm and a relative density greater than 95%. The iridium and iridium alloy materials have a grain size of 0.5-20 μm and a preferred orientation of the grains, with the oriented crystal planes being one or more of (111), (200), and (220).

[0025] The present invention provides the above-mentioned iridium and iridium alloy materials as iridium sputtering targets or ultra-high temperature materials for application in the field of information storage or the field of high-temperature structural materials.

[0026] Advantageous Effects of the Invention

[0027] The present invention relates to a method for preparing iridium and iridium alloy materials, a key core technology in the fields of information storage and high-temperature structural materials. This method improves the purity of the blank through hydrogen atmosphere degassing and impurity removal. It also uses a high-strength ceramic indenter for in-situ vacuum, die-less hot rolling and slow deformation, increasing material density and preventing impurity contamination. This solves mold usage challenges and enables the preparation of large-scale, high-performance iridium and iridium alloy materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a microscopic morphology photo of the iridium powder raw material in Example 1

[0029] Figure 2 The X-ray diffractometer spectrum of the iridium powder raw material of Example 1

[0030] Figure 3 This is the X-ray diffractometer spectrum of the iridium sputtering target prepared in Example 1

[0031] Figure 4 This is the X-ray diffractometer spectrum of the iridium sputtering target prepared in Example 2

[0032] Figure 5 This is a microstructure photo of the iridium sputtering target prepared in Example 1 DETAILED DESCRIPTION

[0033] The present invention will be further described below by way of examples. The following examples are only provided for understanding the present invention and are not intended to limit the present invention.

[0034] Example 1

[0035] 1. Select iridium powder with a purity of 99.9%, its morphology is shown in Figure 1 , and its X-ray diffractometer pattern is shown in Figure 2 , weigh 850.5g and fill it into a steel mold made of Cr12MoV.

[0036] 2. Maintain the pressure in a steel mold at 250 MPa for 3 minutes, and demold to obtain an iridium blank with a diameter of 40 mm and a thickness of 30 mm.

[0037] 3. Place the iridium blank in an alumina corundum crucible and place it in a hydrogen furnace. Heat it at 1200°C in a hydrogen atmosphere for 30 minutes. After cooling in the furnace, take out the iridium blank with improved purity.

[0038] 4. Place the hydrogen-treated iridium blank in a vacuum hot pressing device and heat it for 10 -3 Pa, 1250 ℃, keep warm for 1h, use silicon nitride ceramic indenter to perform in-situ vacuum moldless hot rolling slow deformation at the same temperature, the pressure is 30MPa, the deformation time is 30min, and after cooling with the furnace, it is taken out to obtain an iridium sputtering target with a diameter of about 110mm, a thickness of about 3mm, and a purity of not less than 99.95%. Its density is 98%, the grain size distribution range is 1-7μm, the grains are (111) preferred orientation, and the organization is uniform. Its X-ray diffractometer spectrum is shown in Figure 3 Its microstructure is shown in Figure 5 .

[0039] Example 2

[0040] 1. Select iridium powder with a purity of 99.9%, weigh 850.5 g, and fill it into an isostatic pressing mold of polyurethane material.

[0041] 2. The mold was sealed and placed in a cold isostatic press. The iridium powder was pressed under a pressure of 250 MPa for 3 minutes. After removal, the mold was demoulded to obtain an iridium blank with a diameter of 40 mm and a thickness of 30 mm.

[0042] 3. Place the iridium blank in an alumina corundum crucible and place it in a hydrogen furnace. Heat it at 1200°C in a hydrogen atmosphere for 60 minutes. After cooling in the furnace, take out the iridium blank with improved purity.

[0043] 4. Place the hydrogen-treated iridium blank in a vacuum hot pressing device and heat it for 10 -4 Pa, 1350 ℃, heat preservation for 90 minutes, at the same temperature, use silicon carbide ceramic indenter to perform in-situ vacuum moldless hot rolling slow deformation, the pressure is 40MPa, the deformation time is 40min, and after cooling with the furnace, it is taken out to obtain an iridium sputtering target with a diameter of about 125mm, a thickness of about 3mm, a purity of not less than 99.95%, a density of 98%, a grain size distribution range of 4-9μm, and a grain with a preferred orientation of (111) crystal plane and a second orientation of (200) crystal plane, with uniform organization. Its X-ray diffractometer spectrum is shown in Figure 4 .

[0044] Example 3

[0045] 1. Select iridium powder with a purity of 99.9%, weigh 1.33 kg, and fill it into an isostatic pressing mold of polyurethane material.

[0046] 2. The mold was sealed and placed in a cold isostatic press. The iridium powder was pressed under a pressure of 250 MPa for 5 minutes. After removal, the mold was demoulded to obtain an iridium blank with a diameter of 50 mm and a thickness of 30 mm.

[0047] 3. Place the iridium blank in an alumina corundum crucible and place it in a hydrogen furnace. Heat it at 1300°C in a hydrogen atmosphere for 90 minutes. After cooling in the furnace, take out the iridium blank with improved purity.

[0048] 4. Place the hydrogen-treated iridium blank in a vacuum hot pressing device and heat it for 10 -4 Pa, 1450℃, keep warm for 90min, and use alumina ceramic indenter for in-situ vacuum moldless hot rolling slow deformation at the same temperature. The pressure is 50MPa and the deformation time is 40min. After cooling in the furnace, it is taken out to obtain an iridium sputtering target with a diameter of about 300mm, a thickness of about 1mm, a purity of not less than 99.95%, a density of 98%, a grain size distribution range of 3-15μm, and a grain preferential orientation of (220) crystal plane with uniform organization.

[0049] Example 4

[0050] 1. Select iridium powder and manganese powder with a purity of 99.9%, and the atomic ratio of Ir to Mn is 0.6:0.4, that is, Ir 0.6 Mn 0.4 521.6 g of iridium powder and 99.7 g of manganese powder were weighed, mixed evenly, and filled into an isostatic pressing mold of polyurethane material.

[0051] 2. The mold is sealed and placed in a cold isostatic press, and the pressure is maintained at 250 MPa for 3 minutes. Cold isostatic pressing is performed on the mold, and the mold is removed to obtain a green body with a diameter of 40 mm and a thickness of 30 mm.

[0052] 3. Place the green body in an alumina corundum crucible and place it in a hydrogen furnace. Keep the temperature at 1150°C for 120 minutes under a hydrogen atmosphere. After cooling in the furnace, take out the iridium-manganese green body with improved purity.

[0053] 4. Place the hydrogen-treated green body in a vacuum hot pressing device and heat it for 10 -2Pa, 1200 ° C, keep warm for 1h, and use silicon nitride ceramic indenter to perform in-situ vacuum moldless hot rolling slow deformation at the same temperature. The pressure is 50MPa and the deformation time is 30min. After cooling with the furnace, it is taken out to obtain an iridium-manganese alloy sputtering target with a diameter of about 120mm, a thickness of about 3mm, a purity of not less than 99.95%, a density of 97%, and a grain size distribution range of 5-13μm.

[0054] Example 5

[0055] 1. Select iridium powder and tantalum powder with a purity of 99.9, and the atomic ratio of Ir to Ta is 0.9:0.1, that is, Ir 0.9 Ta 0.1 755.2 g of iridium powder and 78.7 g of tantalum powder were weighed, mixed evenly, and filled into an isostatic pressing mold of polyurethane material.

[0056] 2. The mold is sealed and placed in a cold isostatic press, and the pressure is maintained at 250 MPa for 3 minutes. Cold isostatic pressing is performed on the mold, and the mold is removed to obtain a green body with a diameter of 40 mm and a thickness of 30 mm.

[0057] 3. Place the blank in an alumina corundum crucible and place it in a hydrogen furnace. Heat it at 1300°C in a hydrogen atmosphere for 90 minutes. After cooling in the furnace, take out the iridium-tantalum blank with improved purity.

[0058] 4. Place the hydrogen-treated green body in a vacuum hot pressing device and heat it for 10 -3 Pa, 1800℃, keep warm for 1h, and use alumina ceramic indenter for in-situ vacuum moldless hot rolling slow deformation at the same temperature. The pressure is 50MPa and the deformation time is 30min. After cooling with the furnace, it is taken out to obtain an iridium-tantalum alloy sputtering target with a diameter of about 115mm, a thickness of about 4mm, a purity of not less than 99.95%, a density of 97%, and a grain size distribution range of 9-17μm.

[0059] Example 6

[0060] 1. Select iridium powder and rhenium powder with a purity of 99.9%, and the atomic ratio of Ir to Re is 0.6:0.4, that is, Ir 0.6 Re 0.4 499.5 g of iridium powder and 322.3 g of rhenium powder were weighed, mixed evenly, and filled into an isostatic pressing mold of polyurethane material.

[0061] 2. The mold is sealed and placed in a cold isostatic press, and the pressure is maintained at 250 MPa for 3 minutes. Cold isostatic pressing is performed on the mold, and the mold is removed to obtain a green body with a diameter of 40 mm and a thickness of 30 mm.

[0062] 3. Place the green body in an alumina corundum crucible and place it in a hydrogen furnace. Heat it at 1200°C in a hydrogen atmosphere for 120 minutes. After cooling in the furnace, take out the green body with improved purity.

[0063] 4. Place the hydrogen-treated green body in a vacuum hot pressing device and heat it for 10 -4 Pa, 2000℃, keep warm for 1h, and use alumina ceramic indenter for in-situ vacuum moldless hot rolling slow deformation at the same temperature. The pressure is 50MPa and the deformation time is 30min. After cooling with the furnace, the iridium-rhenium alloy with a diameter of about 110mm, a thickness of about 5mm and a purity of not less than 99.95% is obtained. It is used as a high-temperature structural material for the coated composite Ir-Re nozzle of the rocket engine combustion chamber, with a density of 96% and a grain size distribution range of 10-18μm.

[0064] Example 7

[0065] 1. Select iridium powder and rhodium powder with a purity of 99.9%, and the atomic ratio of Ir to Rh is 0.5:0.5, that is, Ir 0.5 Rh 0.5 430.6 g of iridium powder and 230.3 g of rhodium powder were weighed, mixed evenly, and filled into an isostatic pressing mold of polyurethane material.

[0066] 2. The mold is sealed and placed in a cold isostatic press, and the pressure is maintained at 250 MPa for 3 minutes. Cold isostatic pressing is performed on the mold, and the mold is removed to obtain a green body with a diameter of 40 mm and a thickness of 30 mm.

[0067] 3. Place the blank in an alumina corundum crucible and place it in a hydrogen furnace. Heat it at 900°C in a hydrogen atmosphere for 150 minutes. After cooling in the furnace, take out the iridium-rhodium blank with improved purity.

[0068] 4. Place the hydrogen-treated green body in a vacuum hot pressing device and heat it for 10 -3 Pa, 1650 ° C, keep warm for 90 minutes, and use silicon carbide ceramic indenter to perform in-situ vacuum moldless hot rolling slow deformation at the same temperature. The pressure is 40MPa and the deformation time is 50min. After cooling with the furnace, the iridium-rhodium alloy with a diameter of about 105mm, a thickness of about 5mm and a purity of not less than 99.95% is obtained. It is used as a high-temperature structural material for high-temperature gas temperature measurement thermocouples of gas turbine engines with a density of 98% and a grain size distribution range of 9-18μm.

[0069] Example 8

[0070] 1. Select iridium powder and platinum powder with a purity of 99.9%, and the atomic ratio of Ir to Pt is 0.5:0.5, that is, Ir 0.5 Pt 0.5412.9 g of iridium powder and 419.1 g of platinum powder were weighed, mixed evenly, and filled into an isostatic pressing mold of polyurethane material.

[0071] 2. The mold is sealed and placed in a cold isostatic press, and the pressure is maintained at 250 MPa for 3 minutes. Cold isostatic pressing is performed on the mold, and the mold is removed to obtain a green body with a diameter of 40 mm and a thickness of 30 mm.

[0072] 3. Place the blank in an alumina corundum crucible and place it in a hydrogen furnace. Keep it at 1150°C in a hydrogen atmosphere for 50 minutes. After cooling in the furnace, take out the iridium platinum blank with improved purity.

[0073] 4. Place the hydrogen-treated green body in a vacuum hot pressing device and heat it for 10 -3 Pa, 1500 ° C, keep warm for 70 minutes, and use silicon carbide ceramic indenter to perform in-situ vacuum moldless hot rolling slow deformation at the same temperature. The pressure is 50 MPa and the deformation time is 35 minutes. After cooling with the furnace, it is taken out to obtain an iridium-platinum alloy with a diameter of about 100 mm, a thickness of about 5 mm, and a purity of not less than 99.95%. It is used as a high-temperature structural material for electrical contacts of gas turbines and spacecraft engines, with a density of 98% and a grain size distribution range of 5-13 μm.

Claims

1. A method for preparing iridium or iridium alloy material, characterized in that: (1) pressing iridium powder or iridium-containing mixed powder by steel die pressing or cold isostatic pressing to obtain a green body, wherein the green body has a relative density of 40% to 60%; (2) deoxidizing and removing volatile impurities by heating the green body obtained in (1) at 600-1400° C. in hydrogen for 5-300 min; (3) heat treating the blank obtained in (2) at 1000-2300°C in vacuum for 5-300 min, then slowly deforming the blank by in-situ vacuum moldless hot rolling at the same temperature, and cooling the blank with the furnace after the deformation is completed to obtain iridium or iridium alloy material; the pressure of the in-situ vacuum moldless hot rolling slow deformation is 5-50 MPa; the vacuum degree is 10 -1 -10 -4 Pa; hot rolling slow deformation time is 5-300min; The iridium or iridium alloy material is used in the field of information storage or high-temperature structural materials; The iridium or iridium alloy material has a thickness of 0.01-50 mm and a relative density of >95%. The iridium or iridium alloy material has a grain size of 0.5-20 μm, a preferred grain orientation, and an oriented crystal plane of one or more of (111), (200), and (220). Other powders in the iridium-containing mixed powder are selected from one or more of manganese, tantalum, platinum, rhenium, tungsten, rhodium, ruthenium, thorium, hafnium, zirconium, niobium, nickel, and aluminum.

2. The method according to claim 1, wherein: The weight percentage of other powders in the iridium-containing mixed powder is 0.01%-60%.

3. The method according to claim 1, wherein: In step (3), the material of the hot rolling slow deformation indenter is ceramic, selected from alumina, zirconium oxide, silicon carbide, silicon nitride or yttrium oxide.

Images